Production of high quality lubricating oils by cold fractionation, extraction, and synthesis



Feb. 27, 1940.

C. L. 0 PRODUCTION OF HIGH QUALITY LUBRICATING OILS BY COLDFRACTIONATION, EXTRACTION, AND SYNTHESIS Filed Nov. 1, 1937 VISCOUS OILSASPHALT ASPHALT- REMOVAL ZDEASPHALTIZED OIL DEWAXING i DE WAXED OILSELECTWE SOLVENT RAFFIQMTE PRODUCTS EXTRA CTION EXTKACT SOLUTION WAXTREATMENT YUNDISSOLVED OIL MXM

INVENTOR.

Patented Feb. 27, 1940 "UNITED STATES PATENT orries PRODUCTION: OFIntel-i QUALITY LUBRI- ,CATING OILS BY ooLn FRAGTIONATION,

EXTRACTION, AND SYNTHESIS Cecilio L. Ocn, Yonkers, N. Y. I ,Ap plicationNovember 1, 1937, Serial No. 172,088

Claims. (01. ice-1s) This invention relates particularly to a processfor removing from viscous hydrocarbon oils containing desirablelubricating oil constituents, such desirable constituents andconstituents hav- 5 ing properties which permit improvement to formdesirable lubricating .oil constituents.

- One of the principal objects of this invention is to provide a methodfor recovering a larger yield of .high quality lubricating oil frominferior viscous oils than are obtained only by a solvent extraction of,such oils by a solvent or solvents intended to extract selectivelyaromatic, naphthenic, and unsaturated hydrocarbons which includeundesirable lubricating oil constituents.

To attain thisobject, this invention provides,

among other things, for a differential separation of valuable,constituents removed by the selective solventextraction, suchconstituents being highly desirable lubricating oil constituents inspite of readily and economically convertible into highly desirablelubricating oil constituents by synthetic With the above and otherobjects in view,

which. will become apparent from a more detailed description following,reference also being made to the self-explanatory schematic flow diagramWhich illustrates suitable principal steps taken in eifectingthisinvention according to one embodiment.

The starting 'oil for this process may be any ents needed in alubricating oil used in crank cases of internal combustion engines, suchas fractions of crude, mixed base of Mid-Continental crude oils,naphthene base oils, asphalt base oils,or parafline base oils,especially fractions or residues boiling above 700 F. In the event thatsuch initial oil is an unrefined oil containing undesirableconstituents, such as asphaltic and resinous substances, it is first tobe refined by using one or 'more of the following steps: Hydrogenation,distillation, filtration through an absorbent material such as clay,asphalt precipitation, as by means of a low boiling hydrocarbon, or anasphalt absorbent solvent.

The hydrogenation is most suitably one which their. cyclic orunsaturated. character and beingv hydrocarbon oil containing the viscousingredi-.

- for the differential extraction of constituents deis of the typeavoiding asphalt formation by use of low temperatures to avoidsubstantial cracking and dehydrogenation. The distillation is one whichis most suitably carried out under vacuum, with the aid of a-gaseousdistillation agent, or both. The filtration may be carried out in thevapor phase in conjunction, with the above described distillation or inthe liquid phasewith an adsorbent contact agent and other known agentswhich aid in removing preformed and m formative asphaltic substances.The asphalt recipitation can be carried out in well known ways at lowtemperatures by the addition of normally gaseous constituents in theliquid phase,

such as light fractions obtained from'stabilizer B:

towers, the precipitated asphaltic material being. settled, centrifuged,or filtered from the dissolved oil. In the solvent extraction of theasphaltic material may be used such selective absorbents as liquidsulphur dioxide, aluminum chloride, aniline saturated with water, etc.,the absorbent and conditions being adjusted to re- I movemainlyasphaltic and very low viscosity index hydrocarbons.

After the asphalt removal, when necessary, the

low asphalt or deasphaltized oil is subjected to a dewaxing, if needed.Some oils will notrequire the dewaxing and in someinstances, such as inthe refining with aluminum chloride, it might be found more desirable toremove the wax before attempting to remove the asphaltic constituents.Also, in using the liquefied normally gaseous hydrocarbons or similarwax precipitants it has been found desirable to first remove resinousand asphaltic materials, which interfere with wax precipitation andwhich contaminate the wax.

The oil with low wax and asphalt content, such as a dewaxed anddeasphaltized oil, as explained, is subjected to a selective solventextraction by a solvent which extracts mainly cyclic and unsaturatedhydrocarbons to produce a rafiinate of high Viscosity index, suchsolvents as liquid sulphur dioxide, aniline, nitro-hydrocarbons,halogen-hydrocarbons, phenol, etc., being used, either alone, with oneanother or in mixtures with solubility enhancing agents, such asanthracene, benzene, turpentine, acetone, etc.

The wax constituents removed in a dewaxing step are convenientlyemployed through a wax treatment to produce an auxiliary solventsirable. in a lubricating oil and susceptible to improvement. This waxtreatment consists in an improvement involving mainly a splitting ofthe.

wax into normally liquid aliphatic molecules including .isomerization orpolymerization into isoparaiiins. Primarily, this treatment is apyrolytic splitting of the wax at low cracking temperatures to avoid theformation of large amounts of naphtha. This can be accomplished by aslow heat treatment of the Wax at temperatures between about 800 to 900F., under a superatmospheric pressure of about 5 to 20 atmospheres ormore, for a period of about 60 minutes or longer. Hydrogen or an inertgas may be used to aid in obtaining the'pressure and preventing drasticcracking. With extension of time the products can be made to polymerizeand isomerize. To shorten the time of treatment the wax may be made todistill over a condensing agent or dehydrating catalyst. It isconsidered that the wax treatment should mainly produce aliphatichydrocarbons boiling above 400 F., and largely composed of isoparaffinsand monoolefins as well as paraffins. Such hydrocarbons as these havebeen found useful in the process of the present invention as auxiliarysolvents in the difierential separation, which is next to be described.

The differential separation or diiierential solvent extraction in thisinvention is intended to separate from low viscosity index oils, suchas, ordinary selective solvent extracts, constituents which are highlyvaluable present in lubricating oils and those which can readily betransformed into valuable lubricating oil constituents. This objectisachieved by the use of a solvent medium which tends to dissolvealiphatic, alkylate'd cyclic hydrocarbons, and substances of similarnature. Such media comprise low boiling organic liquids of low polaritysuch as carbon tetra-chloride, higher alcohols such as amyl alcohol orisobutanyl oil (synthetic higher alcohols from reduction of carbonmonoxide), alcohol esters, and

such media diluted with gasoline hydrocarbons of paraiiinic character.To supplement the action of such media it has been found helpful to usea mutually soluble high boiling normally liquid aliphatic compound suchas is obtained by the Wax treatment described above, or similar oilssuch as hydrogenated aliphatic polymers produced by the hydrogenation ofpolymers from gum forming constituents in gasoline and keroor more ringsto a molecule, is commercially valuable for forming resins. It isbelieved that this differential separation is aided not only by the kindof auxiliary solvent described but also by the preliminary step of thedeasphaltizing.

The dissolved desirable lubricating constituents may be removed from thediiferential solvent extract solution by distillation and be addeddirectly to the raffinate from the selective solvent extraction toenhance the recovered lubricating oil without further treatment, or thesolution may be subjected to a treatment for synthesizing improvedlubricating oil constituents. In using a solvent such as carbontetra-chloride, which remains more or-less inert or at least not detrimental to the synthesizing treatment, such a 5 medium need not beremoved from the extract from the differential separation for it .iseven The synthesizing treatbeneficial as 'a diluent. ment for improvingthe differential extracted constituents along with the auxiliary solventconstituents consists in a reaction of such constituents. to causefurther alkylation of the ex-' tracted constituents and polymerizationof aliphatics in the auxiliary solvent. This treatment may beaccomplished by subjecting the extract solution from the difierentialseparation includ-j ing such a medium as carbon tetrachloride to theaction of aluminum chloride or a similar Friedel-Crafts condensationagent, or to such an agent with the aid of a promoter, such as a.hydrogen halide. halogenating part of the treated wax. productslubricating oil to do the same.

This may be accomplished by d before they are added to the difierentialsepara- 1 I Asa specificexample, a lvIid-Continent crude lubricatingstockcf viscosity index between 75' and is first deasphaltized bytreatmentwith liquid sulphur dioxide added in an amount of about onethird theweight of the oil treated,

after mixing at a temperature of about 30 F.,

the. mixture being allowed to stratify. An ex tract of very lowviscosity index is removed. The deasphaltized oil is mixed with abutane-propane fraction from a stabilizer tower and coo-led to about 10to cause separation of wax, which is filtered 01f. The dewaxed oilseparated from volatiles, is cooled and mixed: with about an equalweight of aniline at about 30 'F., for selective solvent extraction.Waxobtained by the dewaxing: of the sulphur dioxide-treated oil isdistilled.

at about 850 F., under a pressure of 15 at mospheres to collect a waxdistillate boiling between about 400 and 600 F. The vapors from of steamand oxygen over 'acatalyst made up of pumice impregnated with phosphoricacid and dehydrated. The aniline is removed from the extract and theextract is mixed with hydrocarbons of the treated wax distillate inabout equal proportion and with a similar proportion of car- I bontetrachloride. Following thorough admixture of these liquids,aseparation of the carbon I tetrachloride solution at about 40 is made,"

or clay treated lubricating oil stock, the sulphur dioxidedeasphaltizingmay' be dispensed with. In place of the butane-propanedewaxing agent,

After about 6 so the still are passed together with a small amount otheragents such as ethylene dichloride may be used. In the Wax treatmentdehydrating catalysts such as activated alumina, clay or thoria, may beused. Or, in place of using the hydrating-dehydrating step to acceleratethe wax treatment, a halogenating-dehalogenating, or simply ahalogenating action may be used, such as is obtained by injectingchlorine into the wax undergoing splitting and passing the vapor over ametal such as aluminum, zinc, etc. It is to be understood that numerousother modifications This process is designed to produce lubricat ingoils with remarkable tenacity or adherence to metal surfaces besidesuitable characteristics of viscosity, viscosity-temperaturecoeflicient, low sludge and. residual carbon content, low pour point,and other proper qualities for a lubricating oil. 1

Although the present invention has been described with specific details,it is to be understood that such details are not intended to limit theinvention, except in so far as set forth in the accompanying claims.

Having described my invention, what I claim and desire to secure byLetters Patent, is as follows:

'1. The method of recovering highquality lu-. bricating oils frominferior lubricating oil stocks which comprises subjecting .alubricating oil stock to a deasphaltizing process, dewaxing such oilwhich has been deasphaltized, selectively sepsaturated character buthaving alkyl side chains which make said constituents soluble in said501- vent medium. I

2. A process for obtaining high quality lubrieating oils from inferiorlubricating stocks substantially free of asphalt and wax, whichcomprises subjecting said lubricating .oil stock to a selective solventextraction by a' solventwhich extracts the relatively low -qualityconstituents of the oil, subjecting extracted constituents from saidselective extraction to a differential separation by aliphatic compoundsderived by splitting Wax hydrocarbons and a mutually solublesolvent todissolve out constituents which are desirable as lubricatingconstituents and which are capable on transformation of forminglubricating constituents by alkylation.

3. A process as in claim 2, in which the mutually soluble solvent iscarbon tetrachloride.

4. A process as in claim 2, in which aliphatic compounds used in thedifferential separation are derived from a distillate fraction higherboiling than gasoline obtained by a splitting of wax molecules.

5. Aprocess as in claim 2, in which the solution from thedifierentialseparation is subjected to a treatment with a condensingcatalyst to cause alkylation of constituents differentially separatedfrom the selective solvent extract.

CECIIIO L. OCON.

